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Royal said in an interview with French television network Canal+ that people should stop eating the popular chocolate spread because harvesting one of its key ingredients, palm oil, leads to deforestation that is damaging the environment.
Nutella is a huge deal in France - the country consumes 26% of all Nutella produced globally by maker Ferrero.
Royal said in the Canal+ interview: "We have to replant a lot of trees because there is massive deforestation that also leads to global warming. We should stop eating Nutella, for example, because it's made with palm oil. Oil palms have replaced trees, and therefore caused considerable damage to the environment."
Ferrero, which also makes the famous Ferrero Rocher chocolates, gets almost 80% of its palm oil from Malaysia and said in February that "it has made commitments to source palm oil in a responsible way."
In 2013, it launched the Ferrero Palm Oil Charter as it "has a significant role to play in leading the sustainable transformation of the palm oil sector" and is committed to using palm oil in a responsible way.
In 2011, France tried to push through a 300% tax on palm oil because of its deforestation effect and the fact that products using palm oil contribute to obesity.
However, in 2012, the draft law - dubbed the "Nutella Law" - was quashed after the French senate rejected the amendment by 186 votes to 155.
The move would've been a huge deal for Malaysia, which is Nutella's largest supplier of palm oil and the world's second largest producer of palm oil behind Indonesia. Half a million people work for the palm oil industry in Malaysia and the sector accounts for 5-6% of Malaysia's GDP.